Welcome to The Visible Embryo
The Visible Embryo Birth Spiral Navigation
Fetal Timeline--- -Maternal Timeline-----News-----Prescription Drugs in Pregnancy---- Pregnancy Calculator----Female Reproductive System

WHO International Clinical Trials Registry Platform

The World Health Organization (WHO) has a Web site to help researchers, doctors and patients obtain information on clinical trials.

Now you can search all such registers to identify clinical trial research around the world!




Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System


Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.

Content protected under a Creative Commons License.
No dirivative works may be made or used for commercial purposes.


Pregnancy Timeline by SemestersDevelopmental TimelineFertilizationFirst TrimesterSecond TrimesterThird TrimesterFirst Thin Layer of Skin AppearsEnd of Embryonic PeriodEnd of Embryonic PeriodFemale Reproductive SystemBeginning Cerebral HemispheresA Four Chambered HeartFirst Detectable Brain WavesThe Appearance of SomitesBasic Brain Structure in PlaceHeartbeat can be detectedHeartbeat can be detectedFinger and toe prints appearFinger and toe prints appearFetal sexual organs visibleBrown fat surrounds lymphatic systemBone marrow starts making blood cellsBone marrow starts making blood cellsInner Ear Bones HardenSensory brain waves begin to activateSensory brain waves begin to activateFetal liver is producing blood cellsBrain convolutions beginBrain convolutions beginImmune system beginningWhite fat begins to be madeHead may position into pelvisWhite fat begins to be madePeriod of rapid brain growthFull TermHead may position into pelvisImmune system beginningLungs begin to produce surfactant
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development

Developmental Biology - E Cigarettes

Why E-cigarette Atomizers Kill

Harmful metals found in vapors of electronic cigarettes...

A team of scientists at the University of California, Riverside, has found the concentration of metals in electronic cigarette aerosols - or vapor - has increased since tank-style electronic cigarettes were introduced in 2013.

Electronic cigarettes, which consist of a battery, atomizing unit, and refill fluid, are now available in new tank-style designs, equipped with more powerful batteries and larger capacity reservoirs for storing more refill fluid. But the high-power batteries and atomizers used in these new styles can alter the metal concentrations that transfer into the aerosol.
"These tank-style e-cigarettes operate at higher voltage and power, resulting in higher concentrations of metals, such as lead, nickel, iron, and copper, in their aerosols. Most of the metals in e-cigarette aerosols likely come from the nichrome wire, tin solder joints, brass clamps, insulating sheaths, and wicks - components of the atomizer unit."

Monique Williams, postdoctoral researcher, Department of Molecular, Cell, and Systems Biology, and first author of the research.

The research paper appears in Scientific Reports. Researchers examined six tank-style electronic cigarettes and found all the aerosols had metals that appeared to originate in the atomizers. Further, they found the model with fewest metal parts in its atomizer had the fewest metals in its aerosol.

Of the 19 metals they screened, aluminum, calcium, chromium, copper, iron, lead, magnesium, nickel, silicon, tin, and zinc were from components in the atomizing units.

"Concentrations of the metals, such as lead, in the aerosols increased with more voltage," says Williams. "Concentrations of some elements - chromium, lead, and nickel - were high enough to be a health concern. We found the concentrations of chromium, copper, lead, nickel, and zinc exceeded the proposed permissible exposure limit from the Occupational Safety and Health Administration."

Chromium, lead, and nickel are known carcinogens. Prolonged exposure to chromium could cause gastrointestinal effects, nasal and lung cancer, respiratory irritation, and lung function impairment. Prolonged exposure to lead could produce vomiting, diarrhea, cardiovascular effects, and lung cancer. Nickel inhalation could cause lung disease, damage to the nasal cavity, lung irritation, lung inflammation, hyperplasia in pulmonary cells, and fibrosis.

The researchers analyzed the following six tanks and their atomizers: Kangertech Protank, Aspire Nautilus tank, Kanger T3S tank, Tsunami 2.4, Smok tank, and Clone. They collected aerosols from these brands using two methods and found the total concentrations of metals varied, ranging from 43 to 3,138 micrograms per liter with the "impinger method" of collection and 226 to 6,767 micrograms per liter with the "cold trap method."
"When batteries with more power are used in these tank-style e-cigarettes, their atomizing units can heat to temperatures greater than 300 C, which could produce harmful byproducts. The presence of heavy metals, including some known carcinogens, in e-cigarette aerosols is concerning because with prolonged exposure they could cause adverse health effects.

"Our data on tank-style e-cigarettes and the concentrations of metals they deliver may be useful to regulatory agencies, health care providers, and consumers."

Prue Talbot PhD, Professor, Cell Biology, and research team leader.

Our purpose was to examine the effect of model, puffing topography (voltage, air-flow, puff interval), and method of collection on 19 elements/metals in aerosols from six tank-style electronic cigarettes (EC). Aerosols were collected from six brands using a cold trap or impinger and various puffing topographies. 19 elements were quantified using inductively coupled plasma optical emission spectroscopy. 16 elements/metals were present and quantified in the aerosols. The total concentrations of elements/metals ranged from 43 to 3,138 g/L with the impinger method of collection and 226 to 6,767 g/L with the cold trap method. The concentrations of individual elements were often similar across brands and across topographies. Some elements (e.g., zinc) were present in most aerosols, while others (e.g., cadmium, titanium, vanadium) were rarely found. Concentrations of some elements (e.g., lead) increased in aerosols as voltage/power increased. The model with fewest metal parts in the atomizer had the fewest metals in its aerosols. Most elements/metals in the aerosols have been found previously in the atomizers of EC. All tank-style aerosols had elements/metals that appeared to originate in the atomizers, and concentrations increased with increasing power. Concentrations of some elements were high enough to be a health concern.

Monique Williams, Jun Li and Prue Talbot.

The authors would like to thank David Lyons and Woody Smith for their assistance with the ICP-OES samples. We also thank Yasmine Khader, Avni Parekh, Shreya Maharana, Dalia Rahmon, Riaz Golshen, Jennifer Stevens, Jazmine Chavez, Michelle Hoa, Jessica Toledo, Vicci Yang, Sanjay Ghai, Eriel Datuin, and Ivana Villarreal for their assistance in the lab. We would also like to thank Teresa Martinez for her helpful suggestions to the manuscript. Research reported in this publication was supported by Grant Number R01DA03649 from the National Institute of Drug Abuse and FDA Center for Tobacco Products (CTP) to P.T. M.W. was partially supported by a Predoctoral Fellowship from the Tobacco-Related Disease Research Program of California (grant #23DT-0101) and Postdoctoral T32 Training Grant Award from the NIH (#T32 ES018827). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the Food and Drug Administration.

Return to top of page.

Oct 4 2019   Fetal Timeline   Maternal Timeline   News  

A typical tank-style electronic cigarette with atomizer. CREDIT I. Pittalwala, UC Riverside.

Phospholid by Wikipedia